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• #/bin/sh in one line

  27 juillet 2012, par GoodGuyGreg

  I'm working on some Haskell project using FFmpeg. I need to batch create from a media folder with MP4 files and create screenshots from all of them. I got the code and am using it on a terminal in Unix. It works, but how do I make it in one line to be executed in system "xxxx" in Haskell ?

  If not using several system"xx"...

  #/bin/sh
  
  for i in $(ls *.mp4)
  
  do
  
      ffmpeg -i $i -vframes 7 -y -ss 10 -s 150x150 -an -sameq -f image2 -r 1/5  $i%1d.jpg
  
  done

  I tried :

  import System.Cmd
  
  function = do{system "#/bin/sh";
  
  system "for i in $(ls *.mp4)";
  
  system "do";
  
  system "ffmpeg -i $i -vframes 7 -y -ss 10 -s 150x150 -an -sameq -f image2 -r 1/5  $i%1d.jpg";
  
  system "done";}

  but it gives a error :

  -vframes: No such file or directory
  
  /bin/sh: Syntax error: "done" unexpected

• How Many Default Languages ?

  26 janvier 2012, par Multimedia Mike — Programming

  I was thinking back to my childhood, when my family first owned a computer. It was an MS-DOS-powered IBM PC. The default OS came with 2 programming environments, such as they were : GW-BASIC and batch files. It was a start, I suppose. I guess most any microcomputer you can name from that era came with some kind of BASIC interpreter. That defined the computer’s “out of the box” programmability.

  Then I started wondering how this compares to computers (operating systems/distributions, really) these days. So I installed a fresh version of the latest Ubuntu Linux version (11.10 as of this writing ; x86_32) and looked for programmability (without installing anything else). This is what I came up with :

  1. gcc/C (only the C compiler ; other components of the GNU compiler collection are installed separately)
  2. Perl
  3. Python
  4. C#, as furnished by Mono
  5. Bash — can’t forget about the shell as a full-featured programming language (sh is also present, but not t/csh)
  6. JavaScript — since Firefox is installed per default, JS counts
  7. GNU Assember — thanks to Reimar for the reminder that if gcc is present, gas necessarily needs to be there as well

  I checked on C++, Objective C, Java, Ada, Fortran, Go, Lua, Ruby, Tcl, PHP, R and other languages I could think of, but the above items were the only ones present by default. At the same time, I checked my Mac OS X (10.6) box and it also has Ruby and PHP installed. It has a bunch of other languages, courtesy of Xcode, so I can’t certify anything about its out of the box programmability.

  Still, I think “embarrassment of riches” pretty well sums it up. I try not to be crotchety old fogey complaining that kids these days don’t know how good they have it ; rather, I’m genuinely excited for anyone who wants to leap into computer programming in this day and age.

• What is ffmpeg, avcodec, x264 ? [closed]

  26 février 2016, par onmyway133

  From wiki, I read that

  FFmpeg is a free software project that produces libraries and programs
  for handling multimedia data. The most notable parts of FFmpeg are
  libavcodec, an audio/video codec library used by several other
  projects, libavformat, an audio/video container mux and demux library,
  and the ffmpeg command line program for transcoding multimedia files.

  So ffmpeg is a wrapper of avcodec ? And I often hear that people encode video with x264 using ffmpeg. So ffmpeg is also a wrapper of x264 ?

  How are they related ?